Cat eye infection: causes, warning signs and safe home care

A cat eye infection usually shows up as a red, watery or gooey eye, sometimes with sneezing. Most cases are treatable, but International Cat Care warns that eye problems can quickly become serious in cats. To show your vet what you’re seeing, you can use our symptom photo check to take a clear picture first.

What does a cat eye infection look like?

According to VCA Animal Hospitals and International Cat Care, common signs include:

• Watering or tearing from one or both eyes
• Discharge that is cloudy, yellow or green, or that dries into crusts
• Red, swollen tissue around the eye
• Squinting, blinking or keeping the eye closed
• The third eyelid showing in the inner corner of the eye
• Pawing or rubbing at the eye

Merck Veterinary Manual notes that a problem in only one eye is more often caused by something like a foreign object, a tear duct problem or dry eye. Problems that start in one eye and spread to the other, or affect both, are more often infections.

What causes eye infections in cats?

Most cat eye infections are a form of conjunctivitis, which is inflammation of the pink lining of the eyelids and the white of the eye. International Cat Care calls it the most diagnosed eye infection in cats.

Feline herpesvirus

Merck Veterinary Manual describes feline herpesvirus as extremely widespread in cats and the most common cause of conjunctivitis. Cornell Feline Health Center explains that the virus can stay hidden in the nerves for life after an early infection. From time to time it escapes, and if it attacks the surface of the eye it can cause ulcers. That’s why some cats get repeat flare-ups, often when stressed or unwell.

Calicivirus and cat flu

International Cat Care reports that more than 90% of cat flu cases are caused by feline calicivirus or feline herpesvirus, and both can cause eye discharge and conjunctivitis. Sneezing, nasal discharge, tiredness and a poor appetite often come with it. See our guides to cat upper respiratory infection and cat sneezing.

Chlamydia

Chlamydia felis is a bacterium that mainly infects the eyes. Merck notes that most affected cats are less than a year old, that signs peak around 9 to 13 days after they start, and that untreated cats can spread it to other cats for months. Treatment is a course of antibiotics prescribed by your vet, often continued for several weeks after the eyes look better to stop it coming back.

What does the color of eye discharge mean?

International Cat Care notes that green or yellow discharge usually means bacteria are involved. Color alone can’t tell you the cause, though, so a vet needs to examine your cat.

Is cat squinting a sign of a corneal ulcer?

It can be. Cat squinting is one of the main signs of a corneal ulcer, which is a sore on the clear front surface of the eye. Cornell lists squinting, eye rubbing, discharge, clouding of the cornea and sensitivity to bright light as signs. VCA describes corneal ulcers as very painful, and notes that the eye may look cloudy as fluid builds up in the cornea.

Common causes include feline herpesvirus, scratches from fights or claws, and things trapped under the eyelid. A vet confirms an ulcer with a drop of fluorescein dye, which turns damaged areas green.

VCA notes that superficial ulcers generally heal within three to five days with treatment. Deeper ulcers can get worse, and if the deepest layer of the cornea breaks, the eye can be permanently damaged. Cornell warns that an advanced ulcer can lead to blindness or loss of the eye. This is why squinting in a cat is not a “wait and see” sign.

Which eye signs are an emergency?

Go to a vet the same day, or to an emergency vet, if you notice any of these:

• A cloudy or bluish eye. This can be a sign of a deep ulcer, glaucoma or inflammation inside the eye.
• A bulging or enlarged eye. Merck explains that high pressure in the eye (glaucoma) can enlarge the eyeball over time, and that a cat with any signs of glaucoma should be seen immediately. Merck adds that an eye pushed out of place by an injury needs to be put back surgically as soon as possible.
• Pupils of different sizes. VCA advises treating a sudden difference in pupil size as an emergency to reduce the chance of permanent vision loss. Merck lists a dilated pupil that doesn’t move normally as an early sign of glaucoma.
• Sudden blindness. International Cat Care names high blood pressure as one of the most common causes of sudden blindness in cats. It can detach the retina at the back of the eye, and quick treatment gives the best chance of saving sight.

Why shouldn’t I use human eye drops on my cat?

Keep your own eye drops away from your cat, even if the eye looks like a simple case of pink eye.

• Steroid drops can make an ulcer worse. VCA warns that steroid eye drops used too soon slow or stop the healing of a corneal ulcer and may cause serious complications. Vets check with a dye test before prescribing them. You can’t see a small ulcer at home.
• Redness-relief drops can poison cats. Pet Poison Helpline lists common redness-relief eye drops and nasal sprays as containing imidazoline decongestants. Even small amounts swallowed can cause vomiting, drooling, a slow heart rate, collapse and death in pets. VCA explains that eye medicine drains through the tear ducts into the mouth, and cats also lick it off their paws.
• Old prescriptions may be wrong this time. VCA cautions that a medicine that helped a previous bout of conjunctivitis may not help, and may even be harmful.

Your vet will choose the right drops or ointment and tell you how often to use them. Keep going for the full course, even when the eye looks better.

How do I clean my cat’s eye safely?

Gentle cleaning keeps your cat comfortable while you wait for a vet visit or during treatment. International Cat Care suggests:

1. Dampen a cotton wool ball with clean water.
2. Wipe gently from the corner of the eye outward.
3. Use a separate cotton ball for each eye, so you don’t spread infection.
4. Dry the area with a soft tissue.
5. Don’t touch the eyeball itself. It hurts, and your cat will resist next time.

Wash your hands before and after. Keep a cat with eye discharge away from other cats if you can, and don’t share bowls or bedding. If your vet prescribes drops or ointment, clean away discharge first, then apply the medicine without letting the tip touch the eye.

When should I take my cat to the vet for an eye infection?

International Cat Care advises that any change in your cat’s eyes should be checked by your vet, because untreated infections can cause permanent damage and even blindness. As a rough guide:

• Go now: any sign in the red box at the top.
• See a vet within a day: yellow or green discharge, red swollen eyes, or eye problems in a kitten.
• Book a visit soon: mild watery eyes that last more than a day or two, or keep coming back.

Your vet will examine the eye, often stain it to look for ulcers, and may measure tear production and eye pressure. They may take a swab to test for herpesvirus or Chlamydia. For typical fees, see what a cat vet visit costs.

Written by the CatsMed Team from the sources above. This guide isn’t reviewed by a veterinarian and isn’t a substitute for one. See how we research.